soundbox/soundbox.py

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Python
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import wave
import numpy as np
import math
# Nombre doctets par échantillon
samp_width = 2
# Valeur maximale dun échantillon
max_val = 2 ** (8 * samp_width - 1) - 1
# Fréquence déchantillonnage (Hertz)
samp_rate = 44100
def add_signal(dest, start, source):
dest[int(samp_rate * start):int(samp_rate * start) + len(source)] += source
def silence(dur):
return np.zeros((int(samp_rate * dur),))
def sine(dur, freq, value=1):
x = np.arange(int(samp_rate * dur))
return value * max_val * np.sin(2 * np.pi * freq * x / samp_rate)
def envelope(attack, decay, release, signal):
total = len(signal)
attack = int(attack * total)
decay = int(decay * total)
release = int(release * total)
sustain = total - attack - decay - release
return signal * np.concatenate((
np.linspace(start=0, stop=1, num=attack, endpoint=False),
np.linspace(start=1, stop=2/3, num=decay, endpoint=False),
np.linspace(start=2/3, stop=2/3, num=sustain, endpoint=False),
np.linspace(start=2/3, stop=0, num=release, endpoint=True),
))
notes = {
'do': 0, 'si#': 0,
'do#': 1, 'reb': 1,
're': 2,
're#': 3, 'mib': 3,
'mi': 4, 'fab': 4,
'fa': 5, 'mi#': 5,
'fa#': 6, 'solb': 6,
'sol': 7,
'sol#': 8, 'lab': 8,
'la': 9,
'la#': 10, 'sib': 10,
'si': 11, 'dob': 11,
}
def note_freq(note, octave):
return (440
* (2 ** (octave - 3))
* math.pow(2, (notes[note] - 9) / 12))
def note_freqs(notes):
return list(map(lambda info: note_freq(*info), notes))
def chord(instr, dur, freqs, value=1):
signal = np.zeros((int(samp_rate * dur),))
for freq in freqs:
signal += instr(dur, freq, value / len(freqs))
return signal
def save_signal(out_name, signal):
with wave.open(out_name, 'w') as file:
file.setnchannels(1)
file.setsampwidth(samp_width)
file.setframerate(samp_rate)
file.writeframesraw(signal.astype('<h').tostring())
def load_signal(in_name):
with wave.open(in_name, 'r') as file:
assert file.getnchannels() == 1
assert file.getsampwidth() == samp_width
assert file.getframerate() == samp_rate
size = file.getnframes()
return np.ndarray((size,), '<h', file.readframes(size))